It's a little bit of everything everyone has different DNA and will respond differently to compounds aka sides, some people get them some dont. As for receptors think of them as a golf ball. Lots of little holes where Test can attach too, or tren, or deca etc. But receptors have so many holes. So let's just look at TREN and TEST. Do the fight for the same receptors, yes they do but not like we all think. Think of Test being captain America, and Tren being the Hulk. One is stronger than they other and can fill that hole on the golf ball better and longer without falling off. Test can attach and hold there get the benfits you need the strength of captian America but does fall off when its shield goes away and turns to estro, and new test will replace that opening (floating test). Tren being the HULK it is, is stronger effects the receptors differently wich in turn gives more sides (not estro sides) but also can make you gain strength much faster cause it stays attached longer (more potent)..
now on to why do others have benfits better one way or the other simple answer your DNA. Yes if you body can do TREN at higher dosage you will gain the look and strength faster than someone on TEST, but the guy that cant take higher TREN will still benefit, just will be behind the other guy. (Again DNA is the key). Everyone will react different but the affects on your receptors are they same, the difference can your receptors hold more TREN or TEST without the sides.... hoped this helped.